The present invention relates to a surgical knife which is provided with means for maintaining the cutting edge of the knife blade in perpendicular relationship with respect to the surface being cut and which provides for directional stability during the cutting operation.
It is well known in the prior art to provide surgical knives in which the depth of the cut into the skin is controlled. For example, the Shahinian U.S. Pat. No. 4,324,044 discloses a knife which is provided with a guard surface which is maintained substantially parallel to the surface to be cut. The guard surface thus limits the initial depth of the cut by preventing the handle of the knife from following the blade into the incision. Similarly, the Beaver U.S. Pat. No. 3,945,117 discloses a surgical knife having a guard which frictionally grips the blade so that the guard may be adjusted on the blade. The guard limits the depth of the cut which may be made into the skin. The Williams U.S. Pat. No. 4,473,076 also provides a surgical knife which permits accurate control of incision depth and further provides for improved visibility of the incision being made. However, there is no teaching in the prior art of a surgical knife in which the knife blade is maintained in a plane which is perpendicular to the skin surface by means of a pair of rollers which smooth the surface of the skin and retain the incision line in vertical orientation with respect to the surface of the skin. The Arnott U.S. Pat. No. 4,062,116 discloses a fabric cutting tool which has a central blade with a pair of guide wheels which assist in moving the cutting tool along a piece of fabric.
According to the present invention, there is provided a scalpel having a roller on each side of the blade at a point spaced rearwardly of the blade tip. The rollers are supported on a shaft which passes through an aperture in the knife blade. The radius of the roller is slightly greater than the distance from the center of the hole in the blade to the knife edge. Thus, the rollers extend beyond the knife edge and roll along the skin surface as the incision is being made. The rollers serve the function of maintaining the knife blade in a perpendicular plane with respect to the skin surface and the rollers further perform the function of smoothing out the skin surface immediately adjacent the cutting edge of the knife blade. The depth of the incision may be controlled by the inclination of the scalpel with respect to the skin, that is, by moving the handle of the surgical knife up or down with respect to the skin surface. The advantage in maintaining the knife blade at a 90.degree. angle with respect to the surface of the skin is to enable the surgeon to maintain directional stability during the formation of the incision so as to provide a more perfect closure. A surgical incision made at a right angle with respect to the skin facilitates subsequent skin closure with the skin edges anatomically coapted in a more precise fashion. More precise skin closure results in primary intention healing with improved scar cosmesis and lessens wound healing complications such as infection and secondary intention healing.
An object of the present invention is to provide a surgical knife with means for retaining the knife blade in a plane perpendicular to the surface of the skin.
Another object of the present invention is to provide a scalpel with a pair of rollers which perform the dual function of maintaining the knife blade in perpendicular relationship to the skin surface and also maintains the skin surface in a smooth even plane as it is being cut.
Other objects and many of the attendant advantages of the present invention will become more readily apparent upon consideration of the following detailed specification in connection with the accompanying drawing wherein :